Retractors provide a surgeon with an access portal or pathway to a surgical site, for example during spine surgeries such as discectomies, laminectomies, facectomies, interbody fusions, pedicle screw fixation and similar procedures. Traditional spine surgeries were conducted utilizing an open procedure resulting in a relatively large incision, disruption or resection of significant soft tissue and long recovery times for patients. Minimally invasive techniques have become increasingly popular, particularly for spine surgeries, wherein relatively small incisions and surgical pathways are utilized to perform surgical procedures on a patient, generally resulting in a smaller incision or several relatively small incisions, less retraction and resection of soft tissue and shorter recovery times for patients in comparison to open procedures. Minimally invasive procedures are, in certain circumstances, able to obtain comparable or improved long term surgical outcomes in comparison to open procedures and may provide short term benefits including reduced post-operative pain, reduced use of post-operative narcotics, reduced tissue disruption, thereby permitting reduced scar tissue and potential benefits if a revision is necessary, reduced blood loss, accelerated recovery time, shorter hospital stays and cosmetically appealing smaller incisions. However, the smaller incision or incisions diminish the line-of-sight for a surgeon to directly view a surgical site, because patient soft tissue often limits a surgeon's ability to view the surgical site.
A common procedure in spine surgeries involves fixing screws to several vertebra and securing the screws and vertebra relative to each other with a rod. Such spinal constructs are typically implanted by mounting enclosed or substantially enclosed cannulae or sleeves to the screws such that the enclosed cannulae or sleeves create a surgical pathway through soft tissue and provide access for the surgeon to the surgical site. Minimally invasive spine instruments utilized for such procedures can be difficult to assemble, limit a surgeons ability to view the surgical site, are bulky and extend a significant distance out of a patient's skin, may detach from the screws during the procedure, are complicated to operate involving many steps, result in procedures involving removal and replacement of multiple instruments, inhibit imaging utilizing a C-arm or Fluoroscope as a result of their size and material composition and may be difficult to detach from the screws at the conclusion of the procedure. In addition, current minimally invasive fixation of screws and placement of rods in spine surgery often result in undesirable levels of trauma to a patient's soft tissue in and around the surgical site, along the surgical pathway and proximate the incision. Once assembled for rod insertion, these conventional minimally invasive systems are typically locked into a predetermined position and inhibit a surgeon's options in adapting their surgical technique to a particular patient's anatomy or in adapting the instruments to implant the components in a manner that would benefit the patient.
Certain conventional, minimally invasive spine instrumentation for the placement of pedicle screws and rods is bulky and complicated to utilize with multiple tool exchanges and complicated steps in mounting, removing, aligning and otherwise manipulating the bulky instrumentation to secure screws in the vertebrae and fix the rod to the implanted screws. A surgeon is often unable to directly visualize the surgical site, the screws and/or the rods once they are implanted in a patient, because of the bulky instruments and the relatively small size of the surgical incisions. Accordingly, a surgeon often relies on fluoroscopy to verify that screws and rods are properly placed in a patient and are securely fixed together. Accurate intra-operative visualization of the implant construct can be difficult for a spine surgeon to verify with fluoroscopy because the relatively bulky metallic instruments attached to the construct are radio-opaque.
In addition, the complicated procedures and instrumentation utilized with certain minimally invasive spine surgeries often require removal and replacement of different instruments through the enclosed cannulas or sleeves, thereby fatiguing a surgeon and extending the time that a patient is in surgery and subjected to anesthesia. Further, complicated procedures and instrumentation can lead to surgical delays, particularly for newly trained or novice surgical staff and surgeons when deciphering the complicated procedures and instrumentation. For example, certain counter-torque tools have been specially designed to fit within or onto minimally invasive spinal cannulas or sleeves that may result in several tool exchanges to tighten locking caps onto spinal rods. Further, the grasping handle of the counter-torque tool of conventional minimally invasive spine surgical sets can impede the surgeons visibility or prevent the use of other instruments during the procedure. Further, locking caps are often introduced through and into the substantially enclosed sleeves or cannulae of conventional systems with a screwdriver that must be removed from the sleeve or cannula several times during the procedure to introduce instruments such as the counter-torque sleeve, a distractor, a compressor or similar instruments. The screwdriver typically a self-retaining tip that has a limited ability to retain the locking cap if the sides of the sleeve or cannula are impacted with the locking cap, resulting in the locking cap becoming detached and falling into the incision, thereby requiring removal of the screwdriver and retrieval of the locking cap through the sleeve or cannula or through one of the minimal incisions. Accordingly, it would be desirable to construct a minimally invasive spine instrument set with a counter-torque tool that is relatively easy to secure to a screw for tightening of a locking cap and is relatively easy to remove and replace so that the instrument is only in the theatre when necessary for tightening purposes. It is also desirable to design and construct an instrument set that permits insertion of the locking cap into a minimally invasive incision utilizing a more robust retaining feature than the self-retaining tip of a screwdriver.
Further, conventional minimally invasive instrument sets often have an unwieldy number of excess protruding parts proximate the incision, often for the purpose of fixing the retractor to the polyaxial bone screw, that can block the surgeon's view of the site. Such unwieldy parts severely inhibit a surgeons ability to visualize the construct at the surgical site and result in generally blind insertion and significant reliance on the instrumentation. Coupled with the metallic composition and bulky size of the instruments, visualization of the construct may not be possible until all of the instruments are removed from the construct and the incision at the conclusion of the procedure. Subsequently, if the finally implanted construct is not acceptable to the surgeon, the bulky and unwieldy instruments may have to be reattached to the construct or the surgeon may need to repair the construct through an open procedure.
The conventional minimally invasive spine instruments are typically bulky and unwieldy to react forces encountered by the relatively long, hollow sleeves or cannulae during final tightening of the locking caps to the pedicle screws. The hollow sleeves or cannulae are typically bulky and stiff specifically at the distal end portions to rigidly hold the arms of the pedicle screws in position during final tightening to prevent splaying of the pedicle screws under final tightening loads. In addition, the hollow sleeve or cannulae are bulky and unwieldy along their length to prevent twisting, splaying or breakage during the final tightening step. This metallic bulk attached to the construct limits visualization, as was described above.